Building wall and tapered interfitting blocks therefor



Dec. 5, 1967 N. HANCOCK BUILDING WALL AND TAPERED INTERFITTING BLOCKS THEREFOR Filed July 9, 1965 2 Sheets-Sheet 1 BY COMM PO-W'Efi-Q AT TORWEYS INVENTOR.

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Dec. 5, 1967 N.L. HANCOCK 3,355,849

BUILDING HALL AND TAPBRED INTERFITTING'BLOCKS THEREFOR Filed July 9, 1965 2 Sheets-Sheet 2 1 L; I I l OZI? F/G.6

A TTORNEYS 43 I United States Patent Ofiice 3,355,849 Patented Dec. 5, 1967 3,355,849 BUILDING WALL AND TAPERED INTERFITTING BLOCKS THEREFOR Norman Lee Hancock, 10439 Garibaldi St, St. Louis, Mo. 63122 Filed July 9, 1965, Ser. No. 470,736 11 Claims. (Cl. 52396) ABSTRACT OF THE DISCLOSURE The block has fiat, front and rear faces and is provided with a W-shaped, ribbed and grooved configuration on its upper and lower sides and on its ends. The ribs and grooves on the upper and lower sides interfit the lower and upper sides respectively of a like block. The ends of the block are tapered and the ribs and grooves formed thereon interfit ribs and grooves formed on the ends of a laterally adjacent block which has a reverse end configuration.

This invention relates generally to improvements in a building wall and to the blocks used in the construction of such wall.

An important object is to provide an improved wall that does not require mortar, but relies on the novel interfitting and sealing characteristics of the blocks.

It is an important objective to achieve a building wall having an aesthetically pleasing appearance which can be constructed easily by interfitting specially formed blocks, thereby resulting in a considerable saving in time, labor and expense. The wall eliminates the heretofore prevalent problem of cracked walls caused by expansion, Weight, settling and vibration. The blocks interfit to form a weather-tight seal and to provide a tighter connection and seal between blocks in proportion to the weight applied to the wall, the blocks serving to distribute the weight both horizontally and vertically throughout the wall.

An important object is realized by the provision of a building block having a pair of longitudinal ribs on its upper side with a corresponding longitudinal groove therebetween, a pair of longitudinal grooves in its lower side with a corresponding longitudinal rib therebetween, and a plurality of ribs and grooves upon its ends extending between the upper and lower sides.

Another important objective is provided by constructing the building blocks with tapered ends.

Still another important object is afiorded by constructing the upper side, lower side and ends of the block with a substantially W-shape, whereby the upper and lower sides of corresponding and compatible blocks will interfit and whereby the ends of compatible blocks will interfit.

An important objective is attained by constructing the intervening rib on the lower side of a lesser depth than the intervening groove on the upper side so that when corresponding and compatible blocks are fitted one on top of the other, there is a space between such rib and groove. This space constitutes a part of a pattern of trapped air insulation medially and longitudinally around each block of the building wall.

Another important object is achieved by the provision of a water-proof gasket on the inverted substantially W-shaped upper side of the building block which seals with the corresponding inverted substantially W-shaped lower side of the vertically adjacent blocks.

Yet another important object is realized by forming a building block of a specific construction having an inverted substantially W-shaped upper side forming a pair of longitudinal top ribs with a corresponding longitudinal top groove therebetween, an inverted substantially W-shaped lower side forming a pair of longitudinal bottom grooves with a bottom rib therebetween, and substantially W-shaped ends tapered from one of the sides to the other, at least one end forming a pair of end grooves with an end rib therebetween, the end grooves extending between the top ribs and bottom grooves, and the end rib extending between the top groove and bottom rib.

An important object is to provide another coacting block of specific construction having an inverted substantially W-shaped upper side forming a pair of longitudinal top ribs with a corresponding longitudinal top groove therebetween, an inverted substantially W-shaped lower side forming a pair of longitudinal bottom grooves with a bottom rib therebetween, and substantially W-shaped ends tapered from one of the sides to the other, at least one end forming a pair of end ribs with an end groove therebetween, the end ribs extending between the top ribs and bottom grooves, and the end groove extending between the top groove and bottom rib.

Another important objective is to provide a building wall that can be quickly and easily constructed by utilizing a plurality of blocks of two types arranged in superimposed rows, the blocks of one type interfitting endwise with laterally adjacent blocks of the other type in the same row, interfitting with subjacent and superjacent blocks of the same type, and partially interfitting with the blocks of different type laterally adjacent the said subjacent and superjacent blocks of the same type.

An important object is attained by a building wall constructed of a plurality of blocks arranged in superimposed rows, each block having a pair of longitudinal top ribs on its upper side with a corresponding longitudinal top groove therebetween, a pair of longitudinal bottom grooves in its lower side with a corresponding longitudinal bottom rib therebetween, the bottom grooves receiving the top ribs and the bottom rib interfitting the top groove of the subjacent block of the next row, and each block having a plurality of ribs and grooves upon its ends extending between the upper and lower sides and interfitting with the end ribs and end grooves of laterally adjacent blocks of the same row.

Another important objective is achieved by tapering the opposed ends of each block from one side to the other, the blocks being alternately disposed in end-to-end relation in each row with the tapers reversed.

It is an important object to provide building blocks that are simple and durable in construction, economical to manufacture and assemble, and which can be utilized by anyone with little or no instruction to construct a building wall.

The foregoing and numerous other objects and advantages of the invention will more clearly appear from the following detailed description of a preferred embodirnent of a building wall and of the building blocks used to construct such wall, particularly when considered in connection with the accompanying drawings, in which:

FIG. 1 is a fragmentary, perspective view of a building wall, partially assembled;

FIG. 2 is a perspective view of a first type of building block;

FIG. 3 is a perspective view of a second type of building block;

FIG. 4 is a cross sectional view of the first type of building block disposed one on the other as seen in a transverse vertical plane;

FIG. 5 is a fragmentary, cross sectional view of the building wall as seen in a longitudinal vertical plane;

FIG. 6 is a top plan view of the first type of block;

FIG. 7 is a side elevational view of the first block;

FIG. 8 is a bottom plan view of the first block;

FIG. 9 is an end elevational view of the first block;

FIG. 10 is a top plan view of the second block;

FIG. 11 is a side elevational view of the second block;

FIG. 12 is an end elevational view of the second block, and

FIG. 13 is a bottom plan view of the second block.

Referring now by characters of reference to the drawings, and first to FIG. 1, it will be understood that the building wall is constructed primarily of two types of building blocks generally indicated at 10 and 11 disposed alternately in superimposed rows, and disposed so that blocks of the same type are located in vertical alignment. The ends of the building wall are completed by suitable end blocks referred to at 12, the end blocks 12 being preferably anchored so as to prevent lateral displacement.

The detailed construction of the first block 10 is best shown in FIGS. 2 and 6 through 9. The block 19 includes substantially flat and parallel front and rear surfaces 13 and 14 respectively. Any one or both of these surfaces 13 and 14 may be curved or arcuate in order to provide a curved outer and/ or inner surface to the building wall when assembled.

The block 19 includes an inverted, substantially W- shaped upper side 15 defining a pair of longitudinal top ribs 16 and 17 and a longitudinal top groove 20 therebetween. A water-proof gasket 21, such as rubber, plastic or impregnated paper including asphalt-impregnated asbestos, is attached to the W-shaped upper side 15 in order to provide a more effective seal.

The block 10 has an inverted, substantially W-shaped lower side 22 defining a pair of longitudinal bottom grooves 23 and 24 with a longitudinal bottom rib 25 therebetween. The block 10 includes opposed, substantially W-shaped ends 26 tapered downwardly from the upper side 15 to the lower side 22. Each of these ends 26 defines a pair of end grooves 27 and 28 with an end rib 30 therebetween. The end groove 27 extends between and interconnects the top rib 16 with the bottom groove 23. The end groove 28 extends between and interconnects the top rib 17 with the bottom groove 24. The end rib 30 extends between and interconnects the top groove 29 with the bottom rib 25.

As will be apparent from FIGS. 4 and 5, the bottom rib 25 of the first block 10 is of a lesser depth than the top groove 20 of a corresponding block 10 in which it fits upon assembly so as to provide an air space 31 extending the length of the block 10 from end-to-end. This space 31 constitutes a portion of an air insulation pattern provided in the interior of the building wall, as will become apparent upon later description of parts and assembly.

Formed vertically through the first block 10 are a pair of spaced holes 32 extending through the upper and lower sides 15 and 22 respectively at the longitudinal axis of such block 10. Specifically, the holes 32 are tapered slightly downwardly and have openings communicating with the top groove 20 and with the bottom rib 25.

The second type of block 11 is best illustrated in FIGS. 3 and 10 through 13 inclusive. This second block 11 includes opposed, front and rear surfaces 33 and 34 respectively. In the embodiment disclosed, these front and rear surfaces 33 and 34 are substantially fiat and parallel.

4 It will be understood that these surfaces 33 and 34 can be curved or arcuate to conform or blend with any corresponding configuration of the surfaces 13 and 14 of the first block 10 to provide a curved outer and/or inner wall face upon assembly of the blocks 10 and 11 into a building wall.

The second block 11 includes an inverted, substantially W-shaped upper side 35 defining a pair of longitudinal top ribs 36 and 37 with a longitudinal top groove 40 therebetween. In addition, the block 11 includes an inverted, substantially W-shaped lower side 41 having a pair of longitudinal bottom grooves 42 and 43 with a longitudinal bottom rib 44 therebetween.

The block 11 has a pair of opposed, substantially W- shaped ends 45 tapered upwardly from the lower side 41 to the upper side 35. Each substantially W-shaped end 45 defines a pair of end ribs 46 and 47 with an end groove 50 therebetween. The end rib 46 extends between and interconnects the top rib 36 with the bottom groove 42. The end rib 47 extends between and interconnects the top rib 37 with the bottom groove 43. The end groove 50 extends between and interconnects the top groove 40 with the bottom rib 44.

A water-proof gasket 51, of a material such as rubber, plastic or impregnated paper including asphalt-impregnated asbestos, is fixed to the upper side 35 and each of the ends 4-5 to provide a more effective seal upon assembly of the two types of blocks 10 and 11 in a building wall.

The bottom rib 44 of each block 11 is of a lesser depth than the top groove 40 of the same type of block 11, and is of a lesser depth than of the top groove 20 of the first block 10 into which such bottom rib 44 interfits upon assembly of the blocks 10 and 11 into the wall construction. This particular structural arrangement provides the longitudinal air space 31 between the bottom rib 44 and the top grooves 26 and 41) of blocks 10 and 11 respectively upon assembly.

The second block 11 includes a pair of longitudinally spaced vertical holes. 32, similar to the holes 32 formed in block 10. These vertical holes 32 are slightly tapered downwardly and extend between and communicate with the upper and lower sides 35 and 41 respectively. More specifically, the holes 32 in block 11 have openings communioating with the top groove 40 and with the bottom rib 44.

From FIGS. 5, 8 and 10, it will be understood that the end rib 30 of each end 26 of the first block 10 is of a lesser depth than the coacting end groove 50 of each end 45 of the second block 11 so as to provide an air space 52 between the rib 30 and groove 51]. This air space 52 extends the entire height of the laterally adjacent blocks 10 and 11 from the upper sides 15 and 35 respectively to the lower sides 22 and 41. As will be apparent from FIG. 5, these end air spaces 52 interconnect the lengthwise longitudinal air spaces 31 at the top and bottom of each block so that a continuous, peripheral air space is formed about each block 11) and 11 at a center vertical and longitudinal plane of the building wall. This continuous peripheral air space about each of the blocks 10 and 11 is formed by the intersecting air spaces 31 and 52. Moreover, it will be importantl noted from FIG. 5 that when the blocks 10 and 11 are assembled in a building wall, the continuous, peripheral air spaces about each block intersect to provide an open pattern of communicating air spaces about each and every block. This air space pattern is enhanced by the vertically aligned holes 32 formed in the blocks 10 and 11, the holes 32 interconnecting and communicating the air spaces 31 at the top and bottom of each block in the wall assembly.

To build a wall with the two types of blocks 10 and 11, each row is constructed by alternately placing the blocks 10 and 11 in laterally adjacent and interfitting relation, the end ribs 46 and 47 of each end of each second block 11 being received in the endgrooves 27 and 28 of each adjacent first block 10, and the end rib 30 of each end of each first block being received in the end groove 50 of each adjacent second block 11. Upon engagement of these laterally adjacent blocks 10 and 11 in interfitting relation, as described previously, the gasket 51 will provide an etfective seal therebetween. The ends of each row are completed by suitable end blocks 12 that are preferably anchored to prevent any longitudinal displacement of the building blocks 10 and 11 from their interfitting endwise engagement.

In placing additional rows of blocks in superimposed relation, it will be noted that the second blocks 11 are in vertical alignment. In other words, each of the second blocks 11 of each row is disposed above and seated on a corresponding second block 11 of the subjacent row. Similarly, the first blocks 10 are in vertical alignment. In other words, each first block 10 of each row is disposed above and seated on a corresponding first block 10 of the subjacent row.

For example, upon seating 21 second block 11 on top of a corresponding second block 11 of a subjacent row, the upper ribs 36 and 37 of such subjacent block 11 will be received in the compatible bottom grooves 42 and 43, while the top groove 40 of such subjacent block 11 will receive the bottom rib 44. Upon interfitting connection of the lower side 41 with the upper side 35 of the subjacent block 11, an eifective seal is realized therebetween, such seal being enhanced by the engagement of the water-proof gasket 51 on the upper side 35 of the subjacent block 11.

In addition, portions of the lower side 41 of the second block 11 will overlap and seat on the upper sides 15 of the first blocks 10 laterally adjacent the supporting subjacent second block 11, the top ribs 16 and 17 of the subjacent first blocks 10 being received in the bottom grooves 42 and 43, while the top grooves 20 of the subjacent first blocks 10 receive the bottom rib 44. The interconnection of these portions of blocks 10 and 11 creates a seal that is enhanced by the water-proof gasket 21 on the upper side 15 of the subjacent first block 10.

Each of the first blocks 10 is supported and seated on a corresponding first block 10 of the subjacent row. The lower side 22 of the first block 10 interfits and engages the upper side 15 of the subjacent block 10. More particularly, the top ribs 16 and 17 of the subjacent block 10 are received in the compatible bottom grooves 23 and 24 respectively, while the top groove 20 of the subjacent block 10 receives the compatible bottom rib 25. This interfitting engagement between the vertically aligned blocks 10 provides an efliective seal therebetween, such seal being enhanced by the provision of the water-proof gasket 21 on the upper side 15 of block 10.

It will be importantly noted that each of the blocks 10 or 11 has an interfitting locking engagement with six other blocks 10 and 11 about its periphery. Moreover, because of the particular construction of the building blocks 10 and 11, and their specific arrangement in the building wall, any load applied to the top of such wall will be distributed vertically downward by each of the blocks 10 and 11, while the first blocks 10 operate to distribute such force laterally or horizontally in each row, thereby distributing the load throughout the wall and creating an even tighter interfitting connection both horizontally and vertically between all of the blocks.

Although the invention has been described by making detailed reference to preferred embodiments, such detail is to be understood in an instructive, rather than in any restrictive sense, many variants being possible within the scope of the claims hereunto appended.

I claim as my invention:

1. A building block comprising:

(a) a body having an inverted substantially W-shaped upper side forming a pair of longitudinal ribs with 6 a corresponding longitudinal groove therebetween (b) an inverted substantially W-shaped lower Sidt forming a pair of longitudinal grooves with a cor responding longitudinal rib therebetween,

(c) the body having its ends tapered from one of sait sides to the other of said sides, and

(d) each end being of substantially W-shape forming ribs and grooves extending between the upper anc lower sides and adapted to interfit reversely formec' substantially W-shaped ends of a compatible block and (e) an equal number of ribs being provided at eacl: end of the body, corresponding ribs at opposite ends having substantially aligned apices.

2. A building block comprising:

(a) a body having an inverted substantially W-shaped upper side forming a pair of longitudinal ribs with a corresponding longitudinal groove therebetween,

(b) an inverted substantially W-shaped lower side forming a pair of longitudinal grooves with a corresponding longitudinal rib therebetween,

(c) the intervening rib on the lower side being of a lesser depth than the intervening groove on the upper side so that when corresponding blocks are fitted one on top of the other, there is a continuous, free air space between the last said rib and groove,

(d) the body having its ends tapered from one of said sides to the other of said sides,

(e) the ends being of substantially W-shape forming ribs and grooves extending between the upper and lower sides and adapted to interfit reversely formed substantially W-shaped ends of a compatible block, and

(f) an equal number of ribs being provided at each end of the body, corresponding ribs at opposite ends having substantially aligned apices,

(g) end ribs being adapted to be of lesser depth than the grooves of such compatible: block to provide a continuous air space between said ribs and grooves and around the block as a Whole.

3. A building block comprising:

(a) a body having an inverted substantially W-shaped upper side forming a pair of longitudinal top ribs with a corresponding longitudinal top groove therebetween,

(b) an inverted substantially W-shaped lower side forming a pair of longitudinal bottom grooves with a bottom rid therebetween,

(c) substantially W-shaped ends tapered from one of said sides to the other, and

(d) each end forming a pair of end grooves with an end rib therebetween, the end grooves extending between the top ribs and bottom grooves, and the end rib extending between the top groove and bottom rib.

4. A building block comprising:

(a) a body having an inverted substantially W-shaped upper side forming a pair of longitudinal top ribs with a corresponding longitudinal top groove therebetween,

(b) an inverted substantially W-shaped lower side forming a pair of longitudinal bottom grooves with a bottom rib therebetween,

(c) substantially W-shaped ends tapered from one of said sides to the other, and

(d) each end forming a pair of end ribs with an end groove therebetween, the end ribs extending between the top ribs and bottom grooves, and the end groove extending between the top groove and bottom rib.

5. A building block comprising:

(a) a body having an inverted substantially W-shaped upper side forming a pair of longitudinal top ribs with a corresponding longitudinal top groove therebetween,

(b) an inverted substantially W-shaped lower side forming a pair of longitudinal bottom grooves with a bottom rib therebetween,

(c) substantially W-shaped ends tapered from the up per side to the lower side, each end forming a pair of end grooves with an end rib therebetween, the end grooves extending between the top ribs and bottom grooves, and the end rib extending between the top groove and bottom rib,

(d) the bottom rib on the lower side being of lesser depth than the top groove on the upper side so that when corresponding blocks are fitted one on top of the other there is a space between the last said rib and groove, and

(e) a water-proof gasket attached on the inverted substantially W-shaped upper side.

6. A building block comprising:

(a) a body having an inverted substantially W-shaped upper side forming a pair of longitudinal top ribs with a corresponding longitudinal top groove therebetween,

(b) an inverted substantially W-shaped lower side forming a pair of longitudinal bottom grooves with a bottom rib therebetween,

(c) substantialy W-shaped ends tapered from the lower side to the upper side, each end forming a pair of end ribs with an end groove therebetween, the end ribs extending between the top ribs and bottom grooves, and the end groove extending between the top groove and bottom rib,

(d) the bottom rib on the lower side being of lesser depth than the top groove on the upper side so that when corresponding blocks are fitted one on top of the other, there is a space between the last sai-d rib and groove, and

(e) a water-proof gasket attached on the substantially W-shaped upper side and ends.

7. In a building wall:

(a) a plurality of blocks arranged in superimposed rows,

(b) each block having an inverted substantially W- shaped upper side forming a pair of longitudinal top ribs with a corresponding longitudinal top groove therebetween,

(c) an inverted substantially W-shaped lower side forming a pair of longitudinal bottom grooves with a corresponding longitudinal bottom rib therebetween.

(d) the bottom grooves receiving and the bottom rib interfitting respectively the top ribs and the top groove of the subjacent block of the next row.

(e) each block having opposed ends tapered from one of said sides to the other,

(f) the blocks being alternately disposed in end-to-end relation in each row with the tapers reversed,

(g) the ends of each block being of substantially W- shape forming ribs and grooves extending between the upper and lower sides and interfitting reversely formed W-shaped ends of laterally adjacent compatible blocks of the same row, and

(h) an equal number of ribs being provided at each opposite end of each block, corresponding ribs at opposite ends having substantially aligned apices.

8. In a building wall:

(a) a plurality of first and second types of blocks arranged in superimposed rows,

(b) the first and second types of blocks each having an inverted substantially W-shaped upper side forming a pair of longitudinal top ribs with a corresponding longitudinal top groove therebetween.

(c) an inverted substantially W-shaped lower side forming a pair of longitudinal bottom grooves with a bottom rib therebetween, and

(d) substantially W-shaped ends tapered from one of said sides to the other, each end of each first type 8 block having a pair of end grooves with an end rib therebetween, the end grooves extending between the top ribs and bottom grooves and the end rib extending between the top groove and bottom rib,

(e) each block of the second type having substantially W-shaped ends tapered from one side to the other side, opposite to the taper of the first type block, each end of each second type block having a pair of end ribs with an end groove therebetween, the end ribs extending between the top ribs and bottom grooves, and the end groove extending between the top groove and bottom rib,

(t) the two types of blocks being alternately disposed in end-to-end relation in each row with the tapers reversed,

(g) each type of block having its bottom grooves receiving and its bottom rib interfitting respectively the top ribs and the top groove of the subjacent block of the same type, and having its W-shaped ends interfitting the W-shaped ends of laterally adjacent blocks of the other type of the same row.

9. A building wall as defined in claim 8, in which:

(h) each type block has the bottom rib on the lower side of lesser depth than the top groove on the upper side so that there is a space between the last said rib and groove of superimposed blocks of adjacent rows, and

(i) each first type block has its end rib at each end of lesser depth than the end groove at each end of each second type block so that there is a space between the last said rib and groove of laterally adjacent blocks of different types in the same row.

10. A building wall as defined in claim 8, in which:

(h) a water-proof gasket is provided on the substantially W-shaped upper side of each block of the first type, and

(i) a water-proof gasket is provided on the substantially W-shaped upper side and ends of each block of the second type,

(j) the gaskets providing effective seals between the blocks when assembled.

11. In a building wall:

(a) a plurality of blocks of first and second types arranged in superimposed rows,

(b) each block of both types having an inverted substantially W-shaped upper side forming a pair of longitudinal top ribs with a corresponding longitudinal top groove therebetween, and

(c) an inverted substantially W-shaped lower side forming a pair of longitudinal bottom grooves with a corresponding longitudinal bottom rib therebetween,

(d) each .block of the first type having ends tapered from the upper side to the lower side, each end being of substantially W-shape forming a pair of end grooves with an end rib therebetween, the end grooves extending between the top ribs and bottom grooves, and the end rib extending between the top groove and bottom rib,

(e) each block of the second type having ends tapered from the lower side to the upper side, each end being of substantially W-shape forming a pair of end ribs with an end groove therebetween, the end ribs extending between the top ribs and bottom grooves, and the end groove extending between the top groove and bottom rib,

(f) each block of the same type having its bottom grooves receiving and the bottom rib interfitting respectively the top ribs and the top groove of the subjacent block of the same type of the next row,

(g) the blocks of the two types being alternately disposed in end-to-end relation in each row with the tapers reversed,

(h) each block of the first type having its top ribs interfitting and its top groove receiving respectively 9 10 part of the bottom grooves and bottom rib of each FOREIGN PATENTS block of the second type laterally adjacent the superjacent block of the same type of the next row, and %222 g i g the ribs and grooves of the substantially W-shaped 2 2 1 2 ma ends of the block of each type interfitting the ribs 5 0 0/19 4 Great f f and grooves of the ends of the laterally adjacent 221,468 2/1925 Great Bntam' blocks of different types in the same row. 611,010 10/1960 Italy- 5 7,596 4/ 1940 Sweden. References Cited UNITED STATES PATENTS l0 FRANK L. ABBOTT, Primary Examiner.

2,624,193 1/1953 Larson 52-574 A. C. PERHAM, Assistant Examiner. 

8. IN A BUILDING WALL: (A) A PLURALITY OF FIRST AND SECOND TYPES OF BLOCKS ARRANGED IN SUPERIMPOSED ROWS, (B) THE FIRST AND SECOND TYPES OF BLOCKS EACH HAVING AN INVERTED SUBSTANTIALLY W-SHAPED UPPER SIDE FORMING A PAIR OF LONGITUDINAL TOP RIBS WITH A CORRESPONDING LONGITUDINAL TOP GROOVE THEREBETWEEN. (C) AN INVERTED SUBSTANTIALLY W-SHAPED LOWER SIDE FORMING A PAIR OF LONGITUDINAL BOTTOM GROOVES WITH A BOTTOM RIB THEREBETWEEN, AND (D) SUBSTANTIALLY W-SHAPED ENDS TAPERED FROM ONE OF SAID SIDES TO THE OTHER, EACH END OF EACH FIRST TYPE BLOCK HAVING A PAIR OF END GROOVES WITH AN END RIB THEREBETWEEN, THE END GROOVES EXTENDING BETWEEN THE TOP RIBS AND BOTTOM GROOVES AND THE END RIB EXTENDING BETWEEN THE TOP GROOVE AND BOTTOM RIB, (E) EACH BLOCK OF THE SECOND TYPE HAVING SUBSTANTIALLY W-SHAPED ENDS TAPERED FROM ONE SIDE TO THE OTHER SIDE, OPPOSITE TO THE TAPER OF THE FIRST TYPE BLOCK, EACH END OF EACH SECOND TYPE BLOCK HAVING A PAIR OF END RIBS WITH AN END GROOVE THEREBETWEEN, THE END RIBS EXTENDING BETWEEN THE TOP RIBS AND BOTTOM GROOVES AND THE END GROOVE EXTENDING BETWEEN THE TOP GROOVE AND BOTTOM RIB, (F) THE TWO TYPES OF BLOCKS BEING ALTERNATELY DISPOSED IN END-TO-END RELATION IN EACH ROW WITH THE TAPERS RESERVED, 7G) EACH TYPE OF BLOCK HAVING ITS BOTTOM GROOVES RECEIVING AND ITS BOTTOM RIB INTERFITTING RESPECTIVELY THE TOP RIBS AND THE TOP GROOVE OF THE SUBJACENT BLOCK OF THE SAME TYPE, AND HAVING ITS W-SHAPED ENDS INTERFITTING THE W-SHAPED ENDS OF LATERALLY ADJACENT BLOCKS OF THE OTHER TYPE OF THE SAME ROW. 